Berkeley scientists say that the Earth’s magnetic field can weaken and dip within just 100 years, before flipping so that compasses point south – an event they admit could wreck the entire world’s power grid and expose the world to deadly cosmic rays.

Earth’s magnetic field is weakening 10 times faster than normal at present, leading geophysicists to predict a flip within a few thousand years – but Discovery news says that could understimate the speed of the change.

Authors such as Robert Felix claim that previous reversals have been associated with mass disruptions such as the extinction of Neanderthal man, and with supervolcano eruptions and other apocalyptic events.

The ‘flip’ occurs regularly, but there has not been a documented instance for 800,000 years.

The Berkeley researchers say that apocalyptic events such as supervolcano eruptions are not likely – but that the flip could leave Earth exposed to cosmic rays which our magnetic field normally shields us from, leading to mutations and cancer in human beings.

Study co-author Paul Renne said, ‘We should be thinking more about what the biologic effects would be.’

When the Earth’s magnetic field flips, compasses will point south instead of north (Picture: Rex)

‘What’s incredible is that you go from reverse polarity to a field that is normal with essentially nothing in between, which means it had to have happened very quickly, probably in less than 100 years,’ said Renne.

‘We don’t know whether the next reversal will occur as suddenly as this one did, but we also don’t know that it won’t.’

Earth’s magnetic field shown in a computer simulation between reversals (Picture: Wikimedia Commons)

NASA has poured water on the idea that magnetic field reversals could lead to an apocalypse, saying in 2012 that, ‘The science shows that magnetic pole reversal is – in terms of geologic time scales – a common occurrence that happens gradually over millennia.

‘While the conditions that cause polarity reversals are not entirely predictable – the north pole’s movement could subtly change direction, for instance – there is nothing in the millions of years of geologic record to suggest that any of the doomsday scenarios connected to a pole reversal should be taken seriously. A reversal might, however, be good business for magnetic compass manufacturers.’